Risk of jaundice following transfusion with pooled plasma or serum.

It has been independently shown by Spurling, Shone, and Vaughan (1946), and by Truelove and Hogben (1947), that the use ofpooled serum or plasma, in contradistinction to whole blood from individual donors, increases the risk of hepatitis following blood transfusion. This conclusion raises the elementary statistical problem: how does reduction of the number of contributors to a blood pool diminish the attendant risk ofjaundice-? The issue derives some practical interest from a radical change of procedure with respect to the number of contributors to a single pool of serum or plasma during recent years. According to information supplied to the Directorate of Hygiene (War Office) by the Ministry of Health. " small pool " material (blood from 10 donors) was issued to selected transfusion centres from June to September, 1945. The writer has not been able to elicit definite information with respect to considerations which determined the decision to adopt the number 10. The object of what follows is to elucidate the issue on the basis of such figures as are available and to clarify what information would be requisite to a precise evaluation of the risks attendant on a particular pool size. According to information supplied by the Army Transfusion Service it was customary throughout the war for soldiers treated with pooled plasma to receive from one to two bottles. For simplicity, we may here assume that each patient received one bottle without detracting from the relevance of the ensuing argument for which the following symbols suffice: